<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .checkbox {
        width: 40px;
        height: 40px;
        border: 2px solid #50BFFF;
        border-radius: 50%;
    }

    .checkbox label {
        display: block;
        width: 20px;
        height: 20px;
        margin: 10px;
        background-color: #4F9FFF;
        opacity: 0;
        border-radius: 50%;
        transition: all 1s;
    }

    .checkbox input[type='checkbox'] {
        display: none;
    }

    .checkbox input[type='checkbox']:checked+label {
        opacity: 1;
    }
</style>

<body>
    <div class="checkbox">
        <input type="checkbox" name="" id="box">
        <label for="box"></label>
    </div>
</body>
<script></script>

</html>